1. Field of the Invention
This invention relates to a synchronizer assembly for vehicular transmissions and, in particular, to an improved pin type synchronizer assembly utilizing an improved blocker pin, and preferably an improved jaw clutch tooth, structure.
2. Description of the Prior Art
Synchronized jaw clutch assemblies for use in change gear transmissions, usually vehicular change gear transmissions, are well known in the prior art and examples thereof may be seen by reference to U.S. Pat. Nos. 3,078,975; 3,548,983; 4,059,178; 4,252,222 and 4,540,074, the disclosures of all of which are hereby incorporated by reference. Pin type synchronizers, also known as "Clark type" synchronizers, are also well known to the prior art as may be seen by reference to U.S. Pat. Nos. 2,667,955; 3,910,390; and 4,018,319, the disclosures of all of which are hereby incorporated by reference.
Pin type synchronizer assemblies generally include an axially slideable clutch collar member that is mounted on a splined portion of a shaft on which a pair of axially spaced gears are rotatably mounted. The clutch collar member is provided with jaw clutch teeth which are adapted to be disposed in engagement with complimentary jaw clutch teeth formed on the rotatable gears for positively clutching a selected one of the gears to the shaft. The clutch collar member is formed with a radially extending flange having a plurality of circumferentially spaced openings therethrough and parallel to the shaft. Disposed through certain ones of these openings are pins which are fixed at their ends with synchronizer rings that are adapted to cooperate with the aforesaid gears. The pins, usually called blocker pins, have reduced central portions that define radially outwardly extending shoulders that are adapted to cooperate with the flange opening edges for blocking relative axial movement of the latter with respect to the synchronizer rings when they are rotating nonsynchronously. Disposed within others of said flange openings are a plurality of longitudinally split spring pin assemblies which are freely received at their ends in recesses formed in the synchronizer rings. The split pin spring assemblies are formed with centrally located annular grooves which are biased into engagement with the peripheries in the openings of the clutch collar member flange by resilient means. As is well known, upon initial axial movement of a clutch collar member, the synchronizer rings are caused to move cojointly therethrough by the pin assemblies.
While change gear transmissions utilizing synchronized jaw clutch assemblies, including split pin type of synchronizer assemblies, are widely used and very commercially successful, especially in connection with relatively heavy duty vehicles, such transmissions are not totally satisfactory as the amount of force the operator is required to apply to the shift lever will abruptly decrease and then abruptly increase as the synchronizing event concludes and the jaw clutch member moves unopposed from its previously blocked position to an axial position whereat the jaw clutch teeth to be engaged come into axial abutment and then into axial engagement. This abrupt change in force required at the shift lever, known as "notchiness", provides a feel to the operator which is at least somewhat objectionable.